The shift started at the beginning of the 2017 with January still dominated by Facebook, providing close to 40 percent of web external traffic. At present it retracted to 26 percent. Google started the year at 34 percent, now leads the market with 44 percent of traffic.
Parse.ly’s data analyzes approximately 2,500 online publishers using its analytic s service, including : the Wall Street Journal, Time Inc., Mashable and Huffington Post.

Conclusion

Various different factors are to blame, some are very obvious ones to consider:

Facebook has rapidly updated its news feed algorithm and any changes to the way Facebook decide to give attention to online publishers are far reaching. In 2016 the social media giant has changed its algorithm to give more importance to friends and family over that of publishers.

Publishing videos on Facebook has become a hit. Any algorithms on Facebook affects native video over text links similarly have an effect on traffic.

More of importance are now AMP stories — typically from news publishers — which are listed at the top of mobile search results as Top Stories, these encourage clicks.

We will see the ongoing trend to be in favor of Google, since Facebook has decided more measures to curb certain negative behavior of users, and those are many Facebook doesn’t like.

Facebook rather sees people paying for ads in order to get more traffic than Google where good SEO is still key to your traffic.